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Biomedical subjects

E Wachter

Publications and source records attributed to E Wachter.

At least 73 records · Page 4Linked to original sources
PubMed1977

Disulfide-linked cyanogen bromide peptides of bovine fibrinogen. II. Isolation and sequence analysis of the chain constituents from the amino terminal region.

Bovine fibrinogen was cleaved with CNBr and the peptide F-CB1 which originates from the amino end of the molecule was purified by chromatographic methods. After reduction and alkylation of F-CB1 three main polypeptide chains could be identified. They were derived from the A alpha chain (F-CB1 alpha), Bbeta chain (F-CB1 beta) and gamma chain (F-CB1 gamma) of fibrinogen and consisted of 54, 143 and 78 amino acid residues, respectively. Thrombin digestion released fibrinopeptide A from F-CB1 alpha and smaller amounts of the peptide Gly-Pro-Arg while fibrinopeptide B was released from F-CB1 beta. Fragment F-CB1 gamma was resistant to thrombin. The sequences of 35 amino acid residues in the portion of F-CB1 alpha adjacent to fibrinopeptide A and of 15 residues in F-CB1 beta beyond fibrinopeptide B were determined. They differ by six and two substitutions, respectively, when compared with the homologous part in human fibrinogen. However, the first 29 amino acid residues in bovine and human F-CB1 gamma were identical. The data show that the cysteine-containing regions and the portions to the right of the site of thrombin cleavage in fibrinogen show much less interspecies variability than that known for the fibrinopeptides.

Amino Acid Sequence↗
PubMed1977

Ordering of cyanogen bromide peptides of type III collagen based on their homology to type I collagen: preservation of sites for crosslink formation during evolution.

The order of the cyanogen-bromide-derived peptides from alpha 1 (III) chains of pepsin-solubilized calf skin collagen was found to be 3A-3B-3C-7-6-1,8,2-4-5-9A-9B. The amino-acid sequences of the NH2-terminal region of all peptides were determined by Edman's automated degradation procedure. The alignment of the peptides along the peptide chain was established by searching for the best homology between the partial sequences of the cyanogen bromide peptides from the alpha 1 (III) chain and the completely known sequence of the alpha 1 (I) chain. Characterization of three cyanogen-bromide-derived double peptides provided confirmation of the deduced order. A sequence Gly-Met-Hyl-Gly-His-Arg-Gly-Phe- was established near the NH2-terminus and a sequence Gly-Ile-Hyl-Gly-His-Arg-Gly-Phe near the COOH-terminus of the alpha 1(III) chain. Identical sequences have been found in the corresponding regions of the alph 1(I) chain. They include hydroxylysine, a site for intermolecular crosslink formation. Because these sequences are conserved during evolution of the collagen molecule, they are probably important for collagen structure and function.

Amino Acid Sequence↗
PubMed1977

Amino acid sequence of toxin III from Anemonia sulcata.

Toxin III, the smallest toxin component of the poison of the sea anemone Anemonia sulcata, is a polypeptide with 27 amino acids. Its structure is stabilized by three disulfide bridges. The amino acid sequence was determined by solid-phase Edman degradation of the aminoethylated derivative. The peptide was coupled to the carrier, porous glass, by thiourea bridges between the alpha-amino group of arginine-1 and the epsilon-amino group of lysine-26 and the isothiocyanate groups of the carrier. Another fraction of the polypeptide was bound by an acid-amide condensation of the C-terminal valine-27 with the aminopropyl group of the carrier. The sequence of toxin III has no regions homologous to the 47-residue toxin II. Comparison with the known partial sequence of toxin I, which contains 46 amino acids (Wunderer, G. & Eulitz, M., in preparation) also fails to reveal homologies.

Amino Acid Sequence↗
PubMed1976

Amino-acid sequence of a coelenterate toxin: toxin II from Anemonia sulcata.

Toxin II from Anemonia sulcata, the main component of the sea anemone venom, consists of 47 amino acid residues which are interconnected by three disulfide bridges. The S-aminoethylated polypeptide was coupled to activated glass beads and sequenced to position 33 by automated solid-phase Edman degradation. Blanks arising from anchor points and the rest of the sequence were determined from tryptic peptides of the [14C]carboxymethylated toxin. Toxin II shows no significant homologies with other known sequences of neurotoxins or cardiotoxins. It might constitute a new class of polypeptide toxins.

Amino Acid Sequence↗
PubMed1975

Tracer and freeze-etching analysis of intra-cellular membrane-junctions in Paramecium with a note on a new heme-nonapeptide tracer.

In paramecia the membranes of alveoli and trichocysts are permanently connected to the cell membrane by membrane-junctions, which consist of membrane-intercalated particles in a regular geometrical arrangement. Trichocysts contain secretory material discharged by exocytosis. In unfixed or fixed cells these two compartments were impermeable to the following tracers: To "microperoxidases", i.e. a cytochrome c-derived heme-nonapeptide and a heme-undecapeptide (WM approximately 1650, 1900) applied in vivo, as well as to lanthanum and cytochrome c used during (La) or after (cytochrome c) fixation. The heme-nonapeptide was prepared by TPCK trypsin digestion of cytochrome c and subsequent purification by Sephadex gel chromatography--a simple and inexpensive new procedure resulting in preparations of high yield and purity. Tracers entered alveoli only when the plasmalemma and the alveolar membranes ruptured upon glutardialdehyde fixation. In no case were transmembraneous channels detectable in regions containing membrane-intercalated particles; this holds true for all tracers used and for freeze-fracture replicas obtained by tantalum-tungsten evaporation. With regard to attachment sites over trichocysts our results do not support the assumptions by others according to which exocytosis would be driven by an osmotic shift via transmembraneous channels (which would be analogous to inter-cellular coupling phenomena mediated by gap-junctions), unless such channels would be assumed to operate as carriers rather than via diffusion. Tracers did not penetrate trichocysts before exocytosis occurred. The functional role of membrane-intercalated particles on trichocyst attachments remains unclear. Despite some resemblance with gap-junctions all types of intra-cellular membrane-junctions investigated are functionally "tight" at the level of "resolution" obtained with tantalumtungsten-shadowing and with the tracers used.

Amino Acid Sequence↗
PubMed1975

The amino acid sequence of the double-headed proteinase inhibitor from canine submandibular glands, III. Sequencing studies.

Canine submandibular glands contain 3 polyvalent, double-headed proteinase inhibitors. The amino acid sequences of the two main inhibitors were determined. They differ only in the substitution of one Lys for a Glu residue. The inhibitor molecules are composed of two halves (domains), one antitryptic and one antichymotryptic. The two domains are covalently linked by 3 amino acid residues. The domains are structurally related to each other and to the sequenced monovalent secretory pancreatic trypsin inhibitors.

Amino Acid Sequence↗